This invention relates to spring applied air pressure released parking brakes for railway vehicles, and it more particularly relates to parking brakes governed jointly by fluid spring handbrake cylinders as well as manual handbrake control devices. It has been proposed, as in the Spalding U.S. Pat. No. 4,033,629, granted July 5, 1977, that a parking brake system having a spring applied and fluid pressure released handbrake cylinder be provided having a special reserve reservoir for providing release pressure to provide handbrake operation in the absence of pressure in the brake pipe. This special reservoir pressure must be carried above normal brake pipe pressure, requiring a special compressor to raise the pressure, and at times the attachment of an additional supply of fluid pressure to the system is required.
An object of the present invention is to provide a parking brake system to overcome limitations in the above described system.
Another object of the present invention is to make operation and release of parking brakes always available by either fluid pressure control or by manual operation.
Another object of the present invention is to automatically reset any manually released handbrake mechanisms when fluid pressure is restored to a handbrake train pipe.
Other objects, purposes and characteristic features of the present invention will be in part obvious from the accompany drawings, and in part, pointed out as the description of the invention progresses.